This invention relates to hydraulic door closer apparatus, and more particularly, to hydraulic door closer apparatus having "assist" or "operating" features to facilitate opening of a door. It relates to the general type of hydraulic door closer illustrated in U.S. Pat. No. 4,019,220 issued Apr. 26, 1977 to Sidney Lieberman, and assigned to the assignee of the present application, in which a spring-urged hydraulic piston is arranged to bias a door to its closed position, with appropriate hydraulic damping. Typically, in the application of apparatus of this sort, a closing force generated by a spring is transmitted between the closer and, depending upon where the closer is mounted, either the door or door frame. For this purpose, it is conventional practice to provide a linkage consisting of one or more links, coupled to the unit and to the door or door frame, as the case may be. In the apparatus shown in U.S. Pat. No. 4,019,220, issued Apr. 26, 1977, a rack and pinion arrangement is used to convert the linear movement of the piston within its cylinder to rotary or oscillating motion of the linkage.
Upon opening of the door, the piston is driven by the pinion against the bias of a return spring and the fluid resistance provided by fluid flow within the device. Movement of the door toward the closed position is caused by unloading of the return spring, and the speed of closing is controlled by appropriate damping provided by the hydraulics.
In certain applications, most notably in the cases of hospitals, old age homes and facilities used by handicapped persons, it is desirable or even required by law that doors normally be closed, yet even the relatively modest opening forces needed to overcome conventional door closers may be excessive for such persons. Indeed, in any facility used by handicapped persons, the resistance to opening generated by conventional closers may be insurmountable.
Apparatus for power-assisted opening of a door, with spring-urged closing, has heretofore been proposed. For example, in U.S. Pat. No. 3,478,468, issued Nov. 18, 1969, to Paul W. Martin, a hydraulic door operating system was proposed in substitution for the familiar hydraulic door closer.
It is the principal object of this invention, however, to provide apparatus in which closing of a door is achieved through the operation of what is essentially a conventional door closer, balanced, or, if desired, over-balanced by a pneumatic actuator associated with it.
It is another object of this invention to provide a mechanically simple door closer, energy efficient in its operation, and relatively easy to install with a minimum of skilled labor, and in particular, requiring no electrical controls.
Other objects will appear hereinafter.
In U.S. Pat. No. 3,875,612, issued Apr. 8, 1975, to Edward J. Poitras, and in numerous others, apparatus has been proposed whereby a door with an associated closer device can be manually moved to selected positions and held there by the action of retained hydraulic fluid, or allowed to close upon the happening of a designated condition.
Also known are devices such as the one shown U.S. Pat. No. 3,934,306 issued Jan. 27, 1976, to Vernie L. Farrix, for a hold-open device, whereby the operation of a door closer is countered until the happening of a contingency such as fire. In accordance with the Farrix, a selectively disengagable brake is operatively associated with the door closer arm, operation of the brake serving to impede closing of the door in response to the urging of the closure.
Such devices do not accomplish the objects of the present invention.
The foregoing and other objects are realized, in a presently preferred form of the invention, by a door closer, essentially conventional in its construction, to which there is assembled a pneumatically controlled and powered actuator, arranged to oppose the biasing force of the return spring of the closer. The door closer in accordance with the invention has a housing providing a cylinder, a piston disposed in the cylinder, and force transmitting means such as a linkage coupled to the piston for transmitting forces to and from the piston. The actuator is coupled to the housing, and applies to the piston forces in opposition to the bias of the return spring.
The actuator in one presently contemplated embodiment of the invention provides an adjustable force sufficient to nearly balance the force of the biasing spring, so that very light forces serve to open the door. In an alternative embodiment, the actuator applies to the piston an adjustable force sufficient to overbalance the biasing force of the spring, thus opening the door in response to operation of the device. In the first case, the so-called "assist" mode, the actuator normally applies a counter-balancing force to the piston, but opening of the door causes a timer to begin operation, which removes the force after an adjustable predetermined interval, thus enabling the closer to operate in the normal fashion to close the door. In the second case, the so-called "operating" mode, the operation of a remotely manually operable switch causes operation of the actuator to overbalance the biasing force of the spring, to open the door. "Timing out" of the timer after release of the switch enables the closer to close the door.